Goodness, glad to hear another here has had the same experience regarding this preamp inverting phase. Ok, all owners go home and reverse polarity on your speakers and see for yourself. I also have that wonderful Stereophile test CD which tests for absolute phase.
Have fun! Your preamps may sound even better with this small tweek - plus it's free!
Another question. Does his DAC invert phase?? I also own the DAC and never asked. Oh my.
Bill